For some time various products have been packaged in large bag shaped packages which comprise paper alone or paper in combination with a thermoplastic film. Such bags are formed using a multilayer material that typically includes a plurality of paper layers, with a relatively thin, flexible plastic film adhered to the inside paper layer, the film serving as a moisture and grease barrier. Typically more than one layer of paper is used, including an outer layer that provides the package with an exterior surface which is highly printable, and an inner layer that provides stiffness to the bag such that it can be self-supporting. These basic characteristics generally provide the package with an overall aesthetic quality that consumers perceive as being desirable. Such paper packaging has been used in a variety of applications, particularly large bags which are used in the bulk packaging of dry granular material such as pet food, livestock feed, sugar, coffee, cookies, cereals, baking products such as cake mixes, crackers, chips, powdered milk, charcoal, cement, fertilizer, lime, pesticides, etc. While the term “large” is difficult to define precisely, as used within this description it refers to bags for carrying 5–10 lbs of material, and often more, such as in the case of bags for pet food or fertilizer. Clearly, because of the significant weight involved, such large bags are highly vulnerable to tearing.
A number of improvements to the bag construction materials have been tried. One example is that of a bag made of an all plastic film laminate. Bags made of all plastic laminates have not, however, been very successful. All plastic laminates, while generally stronger on a pound per pound basis when compared with paper, result in a product i) with an outer surface that tends to be slippery, presenting stacking problems; ii) that has poor self standing characteristics unless made with at least one fairly thick layer; and iii) having an exterior surface that is often difficult to print on. Also, such plastic laminate bags tend to be more costly because their manufacture requires replacement of bag making machinery that are tooled for producing multi-wall kraft bags.
In response, composite laminates of both paper and plastic film were developed and are now the structure of choice for large bags intended to contain granular or small particle material such as pet foods. The material of choice for such composite laminates appears to be a laminated structure having an internal multilayer coextruded plastic film grease barrier layer glued to a first strength providing inner paper layer which in turn is glued to a second outer paper layer having desired printability and consumer appeal. Additionally, a composite of film reinforced with a scrim film has also been proposed as a bag material, as disclosed in U.S. Pat. No. 4,340,558 issued to Hendrickson on July 20.
Composites of paper and film, while they remain the material of choice in the manufacture of large size bags for granular consumables, pet foods, fertilizer and the like, where printability, water impermeability, self standing and the ability to stand to abuse properties are important, do unfortunately present cost problems. Specifically, due to severe cost reduction pressures being experienced by the industry, there remains a continuing need to provide such bags that are inexpensive to manufacture without loss of the desirable properties of the currently preferred plastic/paper composites.
One way to effectuate cost reduction is to reduce the manufacturing cost of any of the materials used in the bag fabrication. Part of the material costs can be traced to the actual fabrication process, and such cost includes production efficiencies and minimization of waste material. It is therefore desirable to develop a bag using materials that are cost effective to produce.